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https://issues.apache.org/jira/browse/LUCENE-10233?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17445032#comment-17445032
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Feng Guo commented on LUCENE-10233:
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[~jpountz] Thanks for the guide! Actually, there can be no case run into the
'add extra words ' logic so far since the old usages are all docBase = 0 and
the new usage (this issue) is using the expert method and do 'or' with an
offset. So what you are worried is a potential risk that cause too much memory
usage right? What if we directly throw an Assert Error if users want to extract
the bitset but docBase != 0? This may remove the potential risk.
I agree with you that a SparseFixedBitSet seems more suitable for the existing
framework and less intrusive, so I implemented it in the newest commit. This
approach looks good to me too, so let's go the way you prefer!
> Store docIds as bitset when leafCardinality = 1 to speed up addAll
> ------------------------------------------------------------------
>
> Key: LUCENE-10233
> URL: https://issues.apache.org/jira/browse/LUCENE-10233
> Project: Lucene - Core
> Issue Type: Improvement
> Components: core/codecs
> Reporter: Feng Guo
> Priority: Major
> Time Spent: 10m
> Remaining Estimate: 0h
>
> In low cardinality points cases, id blocks will usually store doc ids that
> have the same point value, and {{intersect}} will get into {{addAll}} logic.
> If we store ids as bitset, and give the IntersectVisitor bulk visiting
> ability, we can speed up addAll because we can just execute the 'or' logic
> between the result and the block ids.
> Optimization will be triggered when the following conditions are met at the
> same time:
> # leafCardinality = 1
> # max(docId) - min(docId) <= 16 * pointCount (in order to avoid expanding
> too much storage)
> # no duplicate doc id
> I mocked a field that has 10,000,000 docs per value and search it with a 1
> term PointInSetQuery, the build scorer time decreased from 71ms to 8ms.
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